The present invention generally relates to cellular communication systems, and, more particularly, to managing uplink (UL) Quality of Service (QoS) in cellular communication systems.
Cellular communication systems provide different types of mobile services including voice, data and multimedia services to users. A cellular communication system includes access points (e.g., macro base stations) to enable wireless connectivity for user equipments (UEs) serviced by the cellular communication system. The UEs often experience varying levels of signal quality depending on their physical location (e.g., indoors, in a basement, etc.) relative to a nearest access point in a particular geographical area. To ensure that UEs receive signals with consistent quality, small-coverage access points (also known as mobile relays) are provided to supplement conventional access points. A mobile relay includes base station and UE subsystems and repeats signals with robust quality to the UEs. The base station subsystem serves as a base station to the UEs and communicates with the UEs using a cellular protocol; the UE subsystem serves as a UE to the macro base station and communicates wirelessly (using a cellular protocol) with the macro base station. Such a cellular communication system is known as a two-hop wireless cellular communication system.
A macro base station may have several (one-hop) UEs that are connected directly and several two-hop UEs that are connected by way of mobile relays. To execute data intensive applications, the UEs are continually required to upload and download data from the internet using the communication system. In a one-hop system, the UE queues the uplink data (UL data) for uploading in a buffer from which the data is transmitted to the macro base station. A medium access control (MAC) scheduler at the macro base station allocates UL slots to each UE that is directly connected to it based on a service level agreement, a buffer occupancy status of the UE, channel conditions, network load, and fairness policies and ensures a UL QoS that meets the service level agreement. If a UE experiences a low UL QoS (e.g., due to channel conditions or high network load) and has excess data queued in its buffers, the MAC scheduler at the macro base station attempts to allocate additional UL slots for the UE to improve the QoS.
In a two-hop system, a UE connected to a macro base station may function as a mobile relay that has multiple UEs connected to it. Similar to the UEs in the one-hop system, the mobile relay provides a buffer occupancy status to the macro base station, which accordingly allocates network resources to the mobile relay. If a UE connected to the mobile relay experiences low UL QoS, the UE may be unable to transmit data to the mobile relay for uploading and consequently its data buffers may be filled. If the mobile relay does not receive upload data, the mobile relay buffers are not queued up and the buffer occupancy status transmitted by the mobile relay shows considerably less data than the actual amount pending for upload. The macro base station performs resource allocation based on the buffer occupancy status and therefore does not allocate enough resources to allow all of the UEs to upload the pending data. Thus, the UEs connected to the mobile relay continue to receive less-than-average UL QoS, which deteriorates the performance of latency sensitive applications.
Therefore, it would be advantageous to have a system for managing UL QoS in a two-hop wireless cellular communication system that ensures consistent UL QoS to two-hop UEs and that overcomes the above-mentioned limitations of conventional cellular communication systems.